Around the world, there has been concern about declines in the abundance of various species of amphibians. Because so little is known about the health and stability of most populations of amphibians, it is unclear how widespread the global decline in amphibians really is.
It appears that species are declining in not only developed areas, where amphibians must compete with human activity, but also in pristine areas, where the water should be unpolluted. This raises the possibility of one or more world-wide phenomena striking wetlands around the globe.
Amphibians as indicators of environmental health
Amphibians have a complicated life history, developing from completely aquatic creatures to mainly terrestrial ones, and they have permeable skin.
Because of this, they act as the proverbial canary in a coal mine, indicating the relative health of their environments.
Causes of amphibian global decline
A number of different causes for a global decline in amphibians have been suggested:
- Acid rain – Acidic precipitation can also fall as snow. When it melts in the spring, it can send a pulse of highly acidic water into breeding ponds, possibly damaging amphibian eggs.
- Airborne pesticides – As merely one example, the pesticide DDT has been found in many areas far from where it was ever sprayed. Even though banned in North America, it is still used in many countries.
- Ultraviolet light – The reduction of the ozone layer in the atmosphere leads to increased ultraviolet (UV) light reaching the Earth's surface. In humans, elevated levels of UV light can lead to increases in the occurrence of cataracts and skin cancer. In amphibians, it may cause damage to eggs floating in ponds.
- Global climate change – World-wide increases in temperatures and associated changes in climates are reducing or altering many aquatic environments, and may be enhancing the effect of the above causes.
Declining Amphibian Populations Task Force (DAPTF)
Whether there is one single cause for amphibian decline, or more likely, a number of different regional causes, it is vital to understand whether this is a signal of greater global change.
To that end, the Declining Amphibian Populations Task Force (DAPTF) was established by the Species Survival Commission of the International Union for the Conservation of Nature (IUCN).
The mandate of the DAPTF is to organize a world-wide amphibian monitoring program to determine four things:
- the status of amphibian populations
- the implications of any declines
- the potential causes of these declines
- policy recommendations based on these findings
To date there are national working groups in a variety of countries, including:
- South Africa
- United Kingdom
In Canada a national working-group has also been formed and there are now coordinators for every province and territory.
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